
Michael Brill and Bob Hunt agree
that R, G, and B tristimulus values
have no units. See Hunt, R.W.G.,
"The Heights of the ClE Colour-
Matching Functions," in
Color
Research and Application,
22 (5):
337 (Oct. 1997).
Image science
In image science, luminance is usually normalized to
a range of I (or occasionally 100) with respect to
a specified or implied white reference, and expressed
without units. The term
luminance
is often used as
shorthand to refer to this unitless quantity; however, it
is properly called
relative luminance.
The term
lumi-
nance .factor
should be avoided for this quantity, since
that ...